On 2/4/21 1:15 PM, Marcelo Tosatti wrote: > On Thu, Jan 28, 2021 at 09:01:37PM +0100, Thomas Gleixner wrote: >> On Thu, Jan 28 2021 at 13:59, Marcelo Tosatti wrote: >>>> The whole pile wants to be reverted. It's simply broken in several ways. >>> I was asking for your comments on interaction with CPU hotplug :-) >> Which I answered in an seperate mail :) >> >>> So housekeeping_cpumask has multiple meanings. In this case: >> ... >> >>> So as long as the meaning of the flags are respected, seems >>> alright. >> Yes. Stuff like the managed interrupts preference for housekeeping CPUs >> when a affinity mask spawns housekeeping and isolated is perfectly >> fine. It's well thought out and has no limitations. >> >>> Nitesh, is there anything preventing this from being fixed >>> in userspace ? (as Thomas suggested previously). >> Everything with is not managed can be steered by user space. > Yes, but it seems to be racy (that is, there is a window where the > interrupt can be delivered to an isolated CPU). > > ethtool -> > xgbe_set_channels -> > xgbe_full_restart_dev -> > xgbe_alloc_memory -> > xgbe_alloc_channels -> > cpumask_local_spread > > Also ifconfig eth0 down / ifconfig eth0 up leads > to cpumask_spread_local. There's always that possibility. We have to ensure that we move the IRQs by a tuned daemon or some other userspace script every time there is a net-dev change (eg. device comes up, creates VFs, etc). > How about adding a new flag for isolcpus instead? > Do you mean a flag based on which we can switch the affinity mask to housekeeping for all the devices at the time of IRQ distribution? -- Thanks Nitesh
